BP reported quarterly earnings of $2.57 billion, beating analysts' expectations of $2.239 billion. Nevertheless, that result is well-below the $3.22 billion reported in the same period last year. The stock was up about 2 percent in premarket trading.

Ford Motor shares tumbled nearly 2 percent ahead of the bell after the automaker reported earnings that were below Wall Street's estimates, citing fewer vehicles sales in North America due to the rollout of the F-150 pickup truck and continued to lose money in South America and Europe.

Merck beat Wall Street's estimates after posting adjusted quarterly profits of 85 cent per share on revenue of $9.4 billion, sending the stock up more than 4.5 percent in premarket trading. Analysts expected the company to report earnings per share of 75 cents on revenue of $9.1 billion.

Pfizer's stock traded slightly lower ahead of the bell after lowering its 2015 guidance for earnings per share and revenue. The pharmaceutical giant also reported quarterly adjusted profits of 51 cent per share on revenue of $10.86 billion, both of which beat Wall Street estimates.

Aetna reported quarterly operating earnings of $2.39 per share, well-above analysts' forecast of $1.95, citing increasing membership since the end of 2014. The U.S.' third-largest health insurer also increased its full-year guidance.

Apple shares rose more than 2 percent ahead of the opening bell as the tech giant carried over its acquired momentum from Monday's earnings report. The company reported quarterly earnings per share of $2.33 on revenue of $56.08 billion, both above consensus estimates. Apple also said it would expand its capital return program to $200 billion from $130 billion.